The entertainment industry requires that lights and light modifying elements such as color changers be moved. Motors and other moving elements, however, are inherent sources of noise. The inventors of the present invention realized that silent operation is highly desirable so that an audience watching a theater production will not be disturbed.
However, there is a trade-off between the speed of movement of various elements and the amount of noise that they produce. Belts and pulleys can be just as noisy as gears, depending on the speed and quality. Belts and pulleys are very noisy when running fast. The first stage of a reduction train runs at speeds which are typically above 1500 rpm. This high speed operation invariably produces noise. At speeds below 1500 rpm, belt and pulley systems become much quieter. This is especially true when noise-reducing mechanisms, such as special tooth-cutting methods, are used. The belt and pulley uses a rubber belt to transmit the force from the driving pulley to the driven pulley. The belt and pulley inherently has low noise transmission and noise vibration. The damping effect of the belt in essence minimizes the transmission of noise and vibration.
Gears, on the other hand, transmit noise directly from the driving gear to the driven gear due to direct contact between the teeth.
The inventor recognized that belts do a very good job of preventing noise transmission so long as they are going slow. The inventor realized, therefore, that a belt in the final stage of the reduction train would help quiet the system. The high speed portion will inherently have noise therein. Since both gears and pulleys will cause noise, the inventors recognized that the quietest solution for the high speed portion is to use small plastic gears with small teeth. This portion will inherently have noise therein.
It is an object of the present invention to isolate this noise and prevent it from travelling through the rest of the system. The inventors recognized that this could be accomplished by allowing any necessary noise to occur at one spot in the unit. That one spot, and hence the noise, is isolated from other places in the unit. Every location which is isolated from the initial noise is formed of low-noise components, such as low-speed belts. Accordingly, the structure of the present invention includes a first movement element which is noisy, a second movement element which is quiet, and a noise isolating structure between said first and second movement elements.
The inventors of the present invention noticed that such noise, although often masked by the sounds of the theater production, can prove very bothersome to the user. In order to obviate this problem, the inventors determined that a certain combination of elements minimizes the noise from such systems.
According to the present invention, a connection between an output shaft of a motor and a pulley is formed using an anti-noise element combination. The pulley is then connected via a belt to a driven shaft. One element of the anti-noise element combination includes a flexible coupling system which has inner surfaces which are substantially the same shape as the outer surface of the driving shafts. Typically these driving shafts are cylindrical. The flexible coupling has elements allowing tightening of these surfaces around the driving shaft. When a specific end of the coupling is tightened, it contracts in size around the shaft, thus tightly gripping the shaft.
Many different kinds of couplings are used. The most preferably used one includes a plurality of circumferential cuts through the middle portion. These cuts, and the material of the coupling, contribute to the ability of the flex coupling to flex in directions which are perpendicular to the axial direction. This has the advantage of minimizing the amount of direct physical noise across the coupling.
Another aspect of the invention relates to the way in which the drive system, the motor, and shaft are mounted to the mounting plate. According to the present invention, rubber grommets are used to minimize driving motor and the plates supporting the pulley system.